Next Article in Journal
Examining the Feasibility of Acoustic Resonance Testing (ART) for Quality Control in Manufacturing
Previous Article in Journal
Self-Adaptive Waste Management System: Utilizing Convolutional Neural Networks for Real-Time Classification
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Engineering Proceedings
Volume 59
Issue 1
10.3390/engproc2023059237
engproc-logo
Submit to this Journal
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Proceeding Paper

Spectral Properties and Biological Activities of Binuclear Mixed-Metal Bridged Thiocyanate Complexes Containing Schiff Bases Derived from Isatin †

by
Adyan Hameed Jasim
1,
Mouayed Yousif Kadhum
1,* and
Sanaa Qasem Badr
2
1
Department of Chemistry, College of Education for Pure Sciences, University of Basrah, Basrah 61004, Iraq
2
Department of Natural Marine Sciences, College of Marine Sciences, University of Basrah, Basrah 61004, Iraq
*
Author to whom correspondence should be addressed.
†
Presented at the International Conference on Recent Advances in Science and Engineering, Dubai, United Arab Emirates, 4–5 October 2023.
Eng. Proc. 2023, 59(1), 237; https://doi.org/10.3390/engproc2023059237
Published: 4 March 2024
(This article belongs to the Proceedings of Eng. Proc., 2023, RAiSE-2023)
Browse Figures
Versions Notes

Abstract

:
This study introduces two novel Schiff base ligands synthesized through the condensation of isatin with primary amines. These ligands were characterized using infrared (IR), ultraviolet-visible (UV-Vis) spectroscopy, mass spectrometry, and elemental analysis. The ligands were further treated with tetrathiocyanate in a 1:1 molar ratio to yield binuclear mixed-metal monomeric bridged complexes of the form LMCd(SCN)4, where M represents Co(II) or Ni(II). Various spectral techniques and magnetic susceptibility measurements were employed for the identification of these complexes. The findings revealed that all the complexes possessed a coordination number of four and exhibited non-electrolytic behavior. Additionally, the cobalt complexes demonstrated paramagnetic properties, whereas the nickel complexes were diamagnetic. The antimicrobial efficacy of the Schiff base ligands and their complexes was also evaluated against selected microorganisms, revealing significant antimicrobial activities.

1. Introduction

Schiff bases are condensation products formed between primary amines and ketones or aldehydes under specific conditions [1]. These compounds are known for their ability to stabilize metal ions in various oxidation states and are involved in a wide range of catalytic and industrial applications. Furthermore, they exhibit extensive biological activities [1,2]. Despite being discovered nearly a century ago, Schiff bases continue to be essential ligands in the realm of metal coordination chemistry. They are especially noteworthy as macrocyclic ligands due to their multifaceted applications [3,4,5]. Isatin-derived Schiff bases are integral in the synthesis of various pharmaceutically active components. These bases are renowned for their antimicrobial, antiviral, and antitumor properties [6,7,8]. Bimetallic thiocyanates that incorporate Schiff bases have also garnered attention, particularly in biological applications, owing to their coordinated systems that feature thiocyanate (SCN) bridges [9,10]. The primary objective of the current research encompasses the preparation, spectroscopic characterization, and biological evaluation of selected Schiff base ligands and their tetrathio-cyanate complexes. These complexes have the general formula [LMCd(SCN)4], where M is either Co(II) or Ni(II) ions, and L represents the Schiff base ligand.

2. Materials and Methods

2.1. Materials

All utilized chemicals, analytical reagents, and metal salts were procured without further purification. Isatin, 2-aminopyridine, and phenyl hydrazine were obtained from Fluka (Buchs, Switzerland), whereas cobalt(II) nitrate, nickel(II) nitrate, potassium thiocyanate, dimethyl sulfoxide (DMSO), methanol, and ethanol were sourced from Sigma-Aldrich (Taufkirchen, Germany).

2.2. Instruments

The melting points of both Schiff base ligands and their complexes were determined using an Electro-Thermal Fisher (Goteborg, Sweden). The elemental composition was ascertained using an ECS-4010 CHNSO NC Technologies (Milano, Italy). The metal content in the complexes was quantified through atomic absorption on phoenix-986 AAS, Sedico Ltd (Nicosia, Cyprus). Infrared spectra, ranging from 400 to 4000 cm−1, were obtained using KBr pellets using FT-IR 84005 Shimadzu (Basrah, Iraq) at room temperature. Ultraviolet-visible (UV-Vis) spectra were measured in ethanol using a UV-1800 Shimadzu (Basrah, Iraq). The 1HNMR and 13CNMR spectra were recorded in DMSO-d6 on a Varian-500 MHZ NMR spectrophotometer (Tehran, Iran). The magnetic susceptibility of the prepared complexes was gauged at room temperature using an MSB-MKI instrument (Baghdad, Iraq) through the Faraday method. Molar conductance values were recorded in dimethylformamide (DMF) at room temperature using a Jenway pcmb conductivity meter (Basrah, Iraq).Mass spectra for the prepared ligands were captured using an MS model 5975C VL MSD (Tehran, Iran) with an electron ionization energy of 70 eV.

2.3. Preparation of Schiff Base Ligands

Ligand L1 was synthesized following a procedure analogous to a previous study [11]. Specifically, 0.55 g (0.002 mol) of isatin was dissolved in 30 mL of ethanol. Separately, 0.18 g (0.002 mol) of 2-aminopyridine was also dissolved in 30 mL of ethanol. Both solutions were combined, and a few drops of glacial acetic acid were added to initiate the reaction. The resulting mixture was subjected to reflux conditions for a duration of 9 h. The product was subsequently filtered and washed with hot ethanol, yielding a compound with a melting point of 235 °C and a yield of 78%. The second ligand, L2, was synthesized following a similar methodology, but employing isatin and phenyl hydrazine as the reactants (Figure 1). The synthesized compound exhibited a melting point of 155 °C and a yield of 82%.

2.4. Preparation of Thiocyanate Complexes

The preparation of thiocyanate complexes was carried out according to established methods [12]. Initially, metal dithiocyanates, specifically [Co(SCN)2, Ni(SCN)2, Cd(SCN)2], were synthesized by reacting metal nitrates with potassium thiocyanate in methanol. The by-product, potassium nitrate, was subsequently removed via filtration. The resultant dithiocyanate solutions were reserved for further reactions. Tetrathiocyanate complexes, denoted as MM’(SCN)4, where M = Co, Ni, and M′ = Cd, were prepared by mixing solutions of M(SCN)2 and M′(SCN)2 in a 1:1 molar ratio, followed by stirring for 36 h. The tetrathiocyanate solutions in methanol were combined with synthesized ligands L1 or L2 in the same solvent in a 1:1 molar ratio. Solid products were obtained, filtered, and washed with ether.
The resultant complexes showed the following properties: L1Co with a melting point of 270 °C and a yield of 75%, L2Co with a melting point of 213 °C and a yield of 79%, L1Ni with a melting point of 280 °C and a yield of 85%, and L2Ni with a melting point of 204 °C and a yield of 83%. The general reaction can be represented as shown in Figure 2.

3. Results and Discussion

3.1. Elemental Analysis

Elemental analysis revealed that the percentages of carbon, hydrogen, nitrogen, cobalt, and nickel in the Schiff base ligands and their complexes closely align with their theoretical values, thereby confirming the proposed chemical formulas for these compounds [11]. The empirical data are summarized in Table 1 and Table 2.

3.2. Spectral Properties

3.2.1. Infrared Spectra

The data are summarized in Table 3 and Table 4. The infrared spectra of the Schiff base ligands and their complexes are illustrated in Figure 3, Figure 4, Figure 5, Figure 6, Figure 7 and Figure 8. For ligands L1 and L2, absorption bands corresponding to the azomethine group appeared at 1620 cm−1 and 1618 cm−1, respectively. These bands shifted to lower wavenumbers in their cobalt and nickel complexes, implicating the azomethine nitrogen in metal ion coordination [11].
The spectra of the prepared complexes also featured new bands in the ranges of 2063–2088 cm−1 and 2137–2148 cm−1, attributed to nitrogen-bonded and sulfur-bonded thiocyanate, respectively [12]. Additionally, bands in the range of 510–573 cm−1 were ascribed to the formation of M–N bonds [13].

3.2.2. Ultraviolet-Visible Spectra

The UV-Vis spectra of the Schiff base ligands and their complexes are presented in Figure 9. The ultraviolet-visible spectra of the Schiff base ligands exhibited absorption bands at 280 nm and 295 nm, respectively, ascribed to π–π* transitions of the azomethine group. Bands appearing at 460 nm for L1 and 404 nm for L2 were suggestive of π–π* transitions in aromatic rings, internal charge transfer, or carbonyl groups [14].

3.3. NMR and Mass Spectra

Both the 1HNMR and 13CNMR spectra of the ligands showed all the expected signals as shown in Figure 10, Figure 11, Figure 12 and Figure 13. The chemical shifts for 1HNMR, 13CNMR are detailed in Table 5 and Table 6, respectively. The mass spectra indicate the presence of molecular ions and other characteristic peaks, further validating the chemical structure of the ligands [13]. The mass spectrum of ligand L2 is shown in Figure 14 and Figure 15.

3.4. Magnetic and Conductivity Measurements

The magnetic susceptibility measurements indicated that the cobalt complexes possessed a tetrahedral geometry and paramagnetic properties, whereas the nickel complexes exhibited a square planar geometry and diamagnetic properties [15]. As shown in Table 7, the molar conductivity and magnetic moments of the complexes exhibit significant variations. Further details are provided in Table 8.

3.5. Biological Activity

The Schiff base ligands and their complexes were tested for antibacterial and antifungal activities against Staphylococcus aureus, Basillus (bacteria) and Candida albicans (fungi). The results demonstrated that all compounds exhibited significant activity, attributed to the presence of the azomethine group and other functional groups [16]. The biological activity data for the ligands and their complexes are detailed in Table 9 and Table 10.

4. Conclusions

This study successfully synthesized Schiff base ligands through the reaction of isatin with 2-aminopyridine or phenyl hydrazine. These ligands were further complexed with MCd(SCN)4, where M represents Co2+ or Ni2+, in a 1:1 molar ratio. Comprehensive characterization was performed using various spectral techniques, confirming the bidentate nature of the ligands. The coordination complexes exhibited a coordination number of four, adopting a tetrahedral geometry for the cobalt complexes and a square planar geometry for the nickel complexes. Notably, both the ligands and their corresponding complexes demonstrated significant antibacterial and antifungal activities, making them potential candidates for further biological studies.

Author Contributions

Methodology and writing—original draft preparation, M.Y.K.; validation, A.H.J.; formal analysis, S.Q.B.; investigation, A.H.J.; resources, S.Q.B.; data curation, A.H.J.; writing—review and editing, M.Y.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

All the data used in the experiment have been made available in the present article.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Reddy, G.N.; Losetty, V.; Yadav, C.H. Synthesis of novel Schiff base metal complexes and their spectroscopic characterization, biological activity and molecular docking investigation. J. Mol. Struct. 2023, 1282, 135161. [Google Scholar] [CrossRef]
  2. Morgan, S.M.; El-Sonbati, A.Z.; Eissa, H.R. Geometrical structures, thermal properties and spectroscopic studies of Schiff base complexes: Correlation between ionic radius of metal complexes and DNA binding. J. Mol. Liq. 2017, 240, 752–776. [Google Scholar] [CrossRef]
  3. Al-Hamdani, A.A.S.; Balkhi, A.M.; Falah, A.; Shaker, S.A. Synthesis and investigation of thermal properties of vanadyl complexes with azo-containing Schiff-base dyes. J. Saudi Chem. Soc. 2016, 20, 487–501. [Google Scholar] [CrossRef]
  4. Sixt, T.; Kaim, W. Copper(I) complexes with N,O-donor Schiff base ligands related to intermediate forms of the TPQ cofactor in amine oxidases. Inorg. Chem. Acta 2000, 300, 762–768. [Google Scholar] [CrossRef]
  5. Singh, D.P.; Grover, V.; Kumar, K.; Jain, K. Metal ion prompted macrocyclic complexes derived from indole-2, 3-dione (isatin) and O-phenylenediamine with their spectroscopic and antibacterial studies. Acta Chim. Slov. 2010, 57, 775-80. [Google Scholar]
  6. Ramu, P.; Prasad, T.A.A.; Vithiyal, S.M.; Antony, S.A. Synthesis, characterization and biological activity of novel spiroheterocycles from isatin derivatives. Der. Pharma Chemica. 2014, 6, 30–36. [Google Scholar]
  7. Lashgari, N.; Ziarani, G.M. Synthesis of heterocyclic compounds based on isatin through 1, 3- dipolar cycloaddition reactions. ARKIVOC 2012, 1, 277–320. [Google Scholar] [CrossRef]
  8. Zlatkovic, M.Z.; Trotev, D.Z.; Stanojevic, J.S.; Todorovic, Z.B.; Cakic, V.S.; Konstantinovic, S.S. Antibacterial activity and photolytic stability of synthesized 5-chloriizatin-3-hydrazone. Adv. Tech. 2018, 7, 41–46. [Google Scholar] [CrossRef]
  9. Kasid, A.T.; Kadhum, M.Y. Synthesis, Characterization And Biological Studies Of Some Bimetallic Bridged Thiocyanate Schiff Base Complexes Based On Carbohydrazide. J. Pharm. Neg. Res. 2022, 13, 1856–1862. [Google Scholar]
  10. Kadhum, M.Y.; Almusawi, B.J. Preparation, identification and antimicrobial studies of some bimetallic bridged thiocyanates complexes containing N,N’-bis (4-isopropyl benzylidene) 4-methyl benzene -1,2-diamine Schiff base ligand. Adv. Appl. Sci. Res. 2015, 6, 120–129. [Google Scholar]
  11. Enad, M.A.; Kadhum, M.Y.; Abdulnabi, A.S. Corrosion Inhibition Efficiency and Adsorption of Azo Schiff Base Chelate Surfactant at Carbon Steel in Hydrochloric Acid Interface. J. Global Pharm. Tech. 2020, 12, 651–656. [Google Scholar]
  12. Upadhayay, N. Synthesis, Characterization and Biological Studies of Some Thiocyanato-bridged Bimetallic Complexes Containing Co(II), Cd(II), Hg(II) and N, N’-Bis(benzylidene)-1,2-phenylenediamine Schiff Base. Chem. Sci. Trans. 2013, 2, 455–460. [Google Scholar]
  13. Singh, D.P.; Malik, V.; Kumar, R.; Kumar, K.; Singh, J. Synthesis and spectral and antibacterial studies of bivalent transition metal ion macrocyclic complexes. Russ. J. Coord. Chem. 2009, 35, 740–745. [Google Scholar] [CrossRef]
  14. Refat, M.S. Synthesis and characterization of norfloxacin-transition metal complexes (group 11, IB): Spectroscopic, thermal, kinetic measurements and biological activity. Spectrochim. Acta Part A Mol. Biomol. Spectrosc. 2007, 68, 1393–1405. [Google Scholar] [CrossRef] [PubMed]
  15. Abd El-Hamid, S.M.; Sadeek, S.A.; El-Farargy, A.F.; Abd El-Lattif, N.S. Synthesis, structural characterization and nematicidal studies of some new N2O2 Schiff base metal complexes. Bull. Chem. Soc. Ethiop. 2021, 35, 315–335. [Google Scholar] [CrossRef]
  16. AL-Jibouri, M.N.; Jawad, W.A.; Balakit, A.A.; Obies, M. Synthesis, Characterization and Theoretical Study of Some Transition Metal Complexes with New Schiff Base Derived from 1,2,4-triazole. Egypt. J. Chem. 2021, 64, 5227–5239. [Google Scholar]
Engproc 59 00237 g001
Figure 1. Synthesis of ligands L1 and L2.
Figure 1. Synthesis of ligands L1 and L2.
Engproc 59 00237 g001
Engproc 59 00237 g002
Figure 2. Synthesis of thiocyanate complexes.
Figure 2. Synthesis of thiocyanate complexes.
Engproc 59 00237 g002
Engproc 59 00237 g003
Figure 3. Infrared Spectrum of ligand L1.
Figure 3. Infrared Spectrum of ligand L1.
Engproc 59 00237 g003
Engproc 59 00237 g004
Figure 4. Infrared Spectrum of complex L1Co.
Figure 4. Infrared Spectrum of complex L1Co.
Engproc 59 00237 g004
Engproc 59 00237 g005
Figure 5. Infrared Spectrum of complex L1Ni.
Figure 5. Infrared Spectrum of complex L1Ni.
Engproc 59 00237 g005
Engproc 59 00237 g006
Figure 6. Infrared Spectrum of ligand L2.
Figure 6. Infrared Spectrum of ligand L2.
Engproc 59 00237 g006
Engproc 59 00237 g007
Figure 7. Infrared Spectrum of complex L2Co.
Figure 7. Infrared Spectrum of complex L2Co.
Engproc 59 00237 g007
Engproc 59 00237 g008
Figure 8. Infrared Spectrum of ligand L2Ni.
Figure 8. Infrared Spectrum of ligand L2Ni.
Engproc 59 00237 g008
Engproc 59 00237 g009
Figure 9. Ultraviolet visible spectra of the Schiff base ligands and their complexes: (a) L1Co; (b) L1Ni; (c) L2Co; (d) L2Ni.
Figure 9. Ultraviolet visible spectra of the Schiff base ligands and their complexes: (a) L1Co; (b) L1Ni; (c) L2Co; (d) L2Ni.
Engproc 59 00237 g009
Engproc 59 00237 g010
Figure 10. 1HNMR spectrum of the ligand L1.
Figure 10. 1HNMR spectrum of the ligand L1.
Engproc 59 00237 g010
Engproc 59 00237 g011
Figure 11. 1HNMR spectrum of ligand L2.
Figure 11. 1HNMR spectrum of ligand L2.
Engproc 59 00237 g011
Engproc 59 00237 g012
Figure 12. 13CNMR spectrum of ligand L1.
Figure 12. 13CNMR spectrum of ligand L1.
Engproc 59 00237 g012
Engproc 59 00237 g013
Figure 13. 13CNMR spectrum of ligand L2.
Figure 13. 13CNMR spectrum of ligand L2.
Engproc 59 00237 g013
Engproc 59 00237 g014
Figure 14. Mass spectrum of ligand L1.
Figure 14. Mass spectrum of ligand L1.
Engproc 59 00237 g014
Engproc 59 00237 g015
Figure 15. Mass spectrum of ligand L2.
Figure 15. Mass spectrum of ligand L2.
Engproc 59 00237 g015
Table 1. The percentage of elements in the Schiff base ligands and their complexes (Part 1).
Table 1. The percentage of elements in the Schiff base ligands and their complexes (Part 1).
Compound.M.wt (g/mol)%C
(cal./found)		%H
(cal./found)		%N
(cal./found)		%Co (cal./found)%Ni (cal./found)
L1224.2264.28/64.323.60/3.5224.99/24.92-/--/-
L2237.2670.87/70.814.67/4.6317.71/17.25-/--/-
L1Co627.8830.61/30.571.28/1.1917.85/17.819.39/9.17-/-
L1Ni627.6430.62/30.591.28/1.2417.85/17.34-/-9.35/9.52
L2Co772.0233.73/33.701.73/1.8215.30/15.519.20/9.43-/-
L2Ni771.7833.75/33.541.73/1.6915.30/15.45-/-9.16/9.82
Table 2. Chemical formulas of the Schiff base ligands and their complexes.
Table 2. Chemical formulas of the Schiff base ligands and their complexes.
Compound.Formula
L1C12H8N4O
L2C12H8N4O
L1CoCoCd(SCN)4C12H8N4O
L1NiNiCd(SCN)4C12H8N4O
L2CoCoCd(SCN)4C14H11N3O
L2NiNiCd(SCN)4C14H11N3O
Table 3. Important infrared bonds of the ligands and their complexes (Part 1).
Table 3. Important infrared bonds of the ligands and their complexes (Part 1).
Sym. of Comp.C-H AromHC=NC=CC=ONH
L13061/31131620156617323412
L1Co3062/31131616158917303404
L1Ni30611617159017373427
L24057/31321618159717283438
L2Co3057/31341616159717323425
L2Ni30591610159717343436
Table 4. Important infrared bonds of the ligands and their complexes (Part 2).
Table 4. Important infrared bonds of the ligands and their complexes (Part 2).
Sym. of Comp.C-N in M- SCNS-C in M-SCNC-N in M-SCN-MM←NM-NSCM-SCN
L1------
L1Co20637482148572507449
L1Ni20737482148573508453
L2------
L2Co20757462137510470447
L2Ni20887482148515468451
Table 5. Chemical shifts of 1HNMR for the Schiff base ligands.
Table 5. Chemical shifts of 1HNMR for the Schiff base ligands.
Ligand1HNMR Chemical Shifts (ppm)
L17.13–7.53 (5H, Ar-H), 8.73 (2H, HC=N-), 13.23 (1H, NH)
L27.10–7.46 (9H, Ar-H), 10.16 (1H, NH-N), 10.20 (1H, NH-CO)
Table 6. Chemical shifts of 13CNMR for the Schiff base ligands.
Table 6. Chemical shifts of 13CNMR for the Schiff base ligands.
Ligand13CNMR Chemical Shifts (ppm)
L1C1(123.08), C2(132.77), C3(113.92), C4(143.95), C5(117.97), C6(125.82), C7(167.66), C8(142.75), C9(161.13), C10(158.14), C11(121.57)
L2C1(122.46), C2(128.49), C3(112.74), C4(138.91), C5(120.09), C6(120.75), C7(167.21), C8(130.05), C9(143.98), C10(115.63), C11(129.22), C12(123.43)
Table 7. Molar conductivity and magnetic moment of the complexes (Part 1).
Table 7. Molar conductivity and magnetic moment of the complexes (Part 1).
Sym. of ComplexFormula of Complexµeff (B.M)Molar MolarMagnetic PropertiesHybridization
L1CoCoCd(SCN)4C15H14N4O5 748.994.03118Paramagneticsp3 (tetrahedral)
Table 8. Molar conductivity and magnetic moment of the complexes (Part 2).
Table 8. Molar conductivity and magnetic moment of the complexes (Part 2).
Sym. of ComplexFormula of Complexµeff (B.M)Molar MolarMagnetic PropertiesHybridization
L1NiNiCd(SCN)4C15H14N4O5748.751.12320Diamagneticdsp2 (square
planar)
Table 9. Biological activity data of the Schiff base ligands and their complexes (Part 1).
Table 9. Biological activity data of the Schiff base ligands and their complexes (Part 1).
CompoundConcentration (mg/mL)Staphylococcus aureusBasillus sp.Candida albicans
L10.0291115
L10.04101117
Table 10. Biological activity data of the Schiff base ligands and their complexes (Part 2).
Table 10. Biological activity data of the Schiff base ligands and their complexes (Part 2).
CompoundConcentration (mg/mL)Staphylococcus aureusBasillus sp.Candida albicans
L10.06101220
L10.08111225
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Jasim, A.H.; Kadhum, M.Y.; Badr, S.Q. Spectral Properties and Biological Activities of Binuclear Mixed-Metal Bridged Thiocyanate Complexes Containing Schiff Bases Derived from Isatin. Eng. Proc. 2023, 59, 237. https://doi.org/10.3390/engproc2023059237

AMA Style

Jasim AH, Kadhum MY, Badr SQ. Spectral Properties and Biological Activities of Binuclear Mixed-Metal Bridged Thiocyanate Complexes Containing Schiff Bases Derived from Isatin. Engineering Proceedings. 2023; 59(1):237. https://doi.org/10.3390/engproc2023059237

Chicago/Turabian Style

Jasim, Adyan Hameed, Mouayed Yousif Kadhum, and Sanaa Qasem Badr. 2023. "Spectral Properties and Biological Activities of Binuclear Mixed-Metal Bridged Thiocyanate Complexes Containing Schiff Bases Derived from Isatin" Engineering Proceedings 59, no. 1: 237. https://doi.org/10.3390/engproc2023059237

Article Metrics

Back to TopTop